Thioester chromogenic substrates for human factor VIIa: substituted isocoumarins are inhibitors of factor VIIa and in vitro anticoagulants.
Arginine thiobenzyl esters are convenient chromogenic substrates of factor VIIa (Z-Arg-SBzl, Kcat/KM = 1,600 M-1 s-1) and were used to study the kinetics of inhibition of factor VIIa by several mechanism-based isocoumarin inhibitors of trypsin-like enzymes. Isocoumarin derivatives substituted with a 7-guanidino or 3-isothiureidopropoxy group were good inhibitors of factor VIIa and acted as anticoagulants in human and rabbit plasma. With normal citrated human plasma, 4-chloro-3-ethoxy-7-guanidinoisocoumarin (3) and 7-amino-4-chloro-3-(3-isothiureidopropoxy) isocoumarin (ACITIC, 6) prolonged the prothrombin time (PT) ca. two-fold and prolonged the activated partial thromboplastin time (APTT) more than 4.5-fold at 20-30 microM. Both compounds had smaller effects in rabbit plasma. The short half-life of ACITIC and related isocoumarins in plasma should make these compounds uniquely useful as anticoagulants in therapeutic situations where it is desirable to have anticoagulant effects for a short defined time period.
Kam
C M
CM
School of Chemistry, Georgia Institute of Technology, Atlanta 30332.
Vlasuk
G P
GP
Smith
D E
DE
Arcuri
K E
KE
Powers
J C
JC
D000595:Amino Acid Sequence; D000925:Anticoagulants; D002863:Chromogenic Compounds / Q000378:metabolism*; D003374:Coumarins / Q000494:pharmacology*; D004952:Esters; D015942:Factor VIIa / Q000037:antagonists & inhibitors*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010314:Partial Thromboplastin Time; D010455:Peptides / Q000378:metabolism; D011517:Prothrombin Time; D013455:Sulfur / Q000378:metabolism
D000925:Anticoagulants; D002863:Chromogenic Compounds; D003374:Coumarins; D004952:Esters; D010455:Peptides; D013455:Sulfur; D015942:Factor VIIa